If a line is actually bisected

[keannu]

Source : 2023, Korean SAT English by Education Broadcasting System, 75p, No 12
The force of gravity dominating our world makes us live in an anisotropic space, that is, space in which dynamics varies with direction. To rise upward means to overcome resistance—it is always a victory. To descend or fall is to surrender to the pull from below, and therefore is experienced as passive compliance. It follows from this unevenness of space that different locations are dynamically unequal. Here, physics can help us, by pointing out that because moving away from the center of gravity requires work, the potential energy in a mass high up is greater than that in one low down. Visually an object of a certain size, shape, or color will carry more weight when placed higher up. Therefore, balance in the vertical direction cannot be obtained by placing equal objects at different heights. The higher one must be lighter. An experimental demonstration with regard to size is mentioned by Langfeld: "If one is asked to bisect a perpendicular line without measuring it, one almost invariably places the mark too high. If a line is actually bisected, it is with difficulty that one can convince oneself that the upper half is not longer than the lower half." This means that if one wants the two halves to look alike, one must make the upper half shorter.
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It will need some knowledge about physics to understand the bold lines, but anyway I have a hard time understanding the second bold lines.
I can understand the first bold line to some extent.
In the second line, why is it saying that it's hard to convince oneself that the upper half is not longer than the lower half? Is it related to the first bold line?

 

[SoothingDave]

This isn't about physics. Or mathematics. It's about how we perceive things visually.

He's saying if you draw a line straight up and down on a page and then attempt to bisect it (divide it into equal halves), you will tend to bisect it too high.

I don't know if that's true or not, but it's what he's saying.

 

[Skrej]

In terms of geometry, bisecting is the act of dividing a line or shape in to two equal parts with another line.

It's saying that it's difficult to visually do this accurately without measuring on something that's vertical (compared to the same thing placed horizontally), because vertical items visually carry more weight. The higher part will always appear bigger than the same part lower down.

Even if you do accurately bisect it by measuring, the top part of a vertical element will still appear larger than the bottom half, even if both parts are actually the same physical size.

So, if you want them to look the same, you have to compensate by making the top part smaller. The two halves will then appear to be the same size, even though physically the bottom is actually larger.

In simpler terms, size is visually distorted when viewed vertically. The same thing placed higher will look bigger.

 

[Tarheel]

Are the students expected to know what "anisotropic" means? (I think Skrej meant dividing.)

 

[keannu]

anisotropic

Students would feel bombarded with tons of unknown knowledge randomly chosen in the test. It's for dividing students into score groups. How would they be prepared to know anisotropic exactly if they haven't understood it exactly in advance?

 

[tedmc]

This isn't about physics. Or mathematics. It's about how we perceive things visually.

He's saying if you draw a line straight up and down on a page and then attempt to bisect it (divide it into equal halves), you will tend to bisect it too high.

I don't know if that's true or not, but it's what he's saying.

I think this has more to do with physics, dealing with potential energy (a function of mass and height, as distinct from kinetic energy) and equilibrium/stability, but I don't know how that can be applied to visual perception.

It is a belief that objects in a high position is in a more advantageous position compared to objects in a low position, which is why we need to compensate for that, by having the halfway mark of a line slightly higher, to maintain equilibrium.

 

[jutfrank]

Are the students expected to know what "anisotropic" means?

No. No reader is expected to know that word, which is why the passage explains what it means.

 

[SoothingDave]

This isn't about physics. You can't use physics to prove that dividing a line into equal halves means you have to divide it unequally.

It's about how we perceive things visually. Not about how they actually are.

 

[Skrej]

I agree, it's not related to physics. If anything, it falls under the guise of psychology and how our brain perceives input.

Regardless, it's ultimately an English test, not a science test. It's just a passage selected to test English ability, particularly reading comprehension.

The Korean SAT English exam is notoriously difficult, even for native English speakers. You can read about it here, and even download a sample exam if you wish (linked in article).

Those reading passages rely heavily on tier-3 and college level academic vocabulary, and are no simple task . They consist of some pretty heavy reading. I can't imagine attempting them as a language learner.

I'll bet too, that at quite a few students who actually do well on the exam still have trouble holding a routine, natural every-day conversation in English. What's being measured in those exams is pretty far removed from normal daily speech, sadly.

 

[tedmc]

If using gravity and the relative positions of objects to explain the potential energy or weightage of objects in space is not related to physics, then what is it related to? Visual perception does not distinguish whether an objects at the top are heavier and those at the bottom are lighter.

 

[Tarheel]

No. No reader is expected to know that word, which is why the passage explains what it means.

They should have explained the explanation. (Just for me. )

 

[keannu]

If using gravity and the relative positions of objects to explain the potential energy or weightage of objects in space is not related to physics, then what is it related to? Visual perception does not distinguish whether an objects at the top are heavier and those at the bottom are lighter.

You are right. The view is only of few professional physicians, but it foces ordinary people to know it.

 

[Tarheel]

You are right. The view is only of few professional physicists, but it forces ordinary people to know it.

It's written for a select audience (physics students). In any case, I don't see how you can force somebody to know something.

 

[jutfrank]

It isn't written for physics students and it isn't about physics. It's written for a general reader, and it's about how we experience the physical world.

 

[Tarheel]

It isn't written for physics students and it isn't about physics. It's written for a general reader, and it's about how we experience the physical world.

If you say so.